BlockMessage

BlockMessage is a tool to send and receive encrypted or plain text messages injected into OP_RETURN Bitcoin based blockchains

As encryption algorithm ECIES is used, so standard BitCoin wallet keys can be used.

Warning: in alpha/PoC state

Warning: current implementation works for KOMODO, not tested in BitCoin nor other blockchains, but it should work just changing few parameters

Usage

The blockchain daemon must be started and synchronized. The RPC port must be reachable, let's assume:

• rpc port 7777
• rpc user bmsg
• rpc pass mypass

First of all, export main wallet keys and an address:

./blockmessage.py --port=7777 --auth=bmsg:mypass -k > mykey

Now let's send a plain text message to Alice, you only need one of his wallet addresses.

./blockmessage.py --port=7777 --auth=bmsg:mypass -s <BOB_ADDRESS>:[AMOUNT_TO_SEND] --text="Hi Alice, Im Bob, this is my public key 02cc2916ca157ace0009db33b4c0926d23b2ee308a264468454e90db99811869bf and here an address for contacting me RHsvnXGs7iWbyQjJuqgi9VodA7RQWcu2ZM"

Alice will be able to read the message by executing:

./blockmessage.py --port=7777 --auth=bmsg:mypass -r 0

Now, let's use encryption! cat mykey will show your public key, this is the one you must share with the people who want to secure communicate with you.

If Alice wants to send an encrypted message to Bob, she must know in advance his public key and a wallet address. This is why Bob has just sent a plain text message to Alice announcing his public key.

Here is how the send encrypted command would look like (from Bob to Alice):

./blockmessage.py --port=7777 --auth=bmsg:mypass -i mykey -s RHsvnXGs7iWbyQjJuqgi9VodA7RQWcu2ZM:1 --encrypt RSA --text="Hi Bob, your weed is cool. Thanks for sharing!" --pubkey=dst_pubkey

Now Bob can read his encrypted messages by executing:

 ./blockmessage.py --port=39967 --auth=vocdoni:vocdoni -i mykey -r 0 --encrypt

That's it!

Command line options

usage: blockmessage.py [-h] [--host RPC_HOST] [--port RPC_PORT]
                       [--auth RPC_AUTH] [-k] [-i KEYSFILE] [-r READ]
                       [-s SEND] [--fee FEE] [--text TEXT] [--encrypt ALGORITHM]
                       [--pubkey DST_PUBKEY]

blockchain tx messaging with encryption

optional arguments:
  -h, --help           show this help message and exit
  --host RPC_HOST      RPC host to connect
  --port RPC_PORT      RPC port to connect
  --auth RPC_AUTH      RPC authentication params (username:password)
  -k                   Print wallet keys and exit
  -i KEYSFILE          File containing own keys (generated with -k)
  -r READ              Read last received messages
  -s SEND              Send a message to address
  --fee FEE            Specify fee for transaction
  --text TEXT          Text to send in message
  --encrypt            Turn on encryption, choose encryption algorithm (RSA by default, ECIES optional)
  --pubkey DST_PUBKEY  If encryption enabled, use destination pubkey